Question

Calculate the pH of a solution obtain by mixing $\text{10} \, \text{ml}$ of $\text{1} \, \text{N}$ sodium acetate and $\text{50} \, \text{ml}$ of $\text{2} \, \text{N}$ acetic acid $\left(\right.K_{a}=1.8\times 10^{- 5}\left.\right),$

• A. 3.74
• B. 5
• C. 6
• D. 7

Answer 1

Answer: (A)

$pH=pK_{a}+log\frac{\left[\right. S a l t \left]\right.}{\left[\right. A c i d \left]\right.}$
$pH=-log\left(\right.1.8\times 10^{- 5}\left.\right)+log\frac{\left[\right. 10 \left]\right.}{\left[\right. 100 \left]\right.}$
$=-log1.8+5+log10^{- 1}$
$=-0.2553+5-1=3.7447$